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iSCSI Optimization
This chapter describes how to configure internet small computer system interface (iSCSI) optimization, which enables quality-
of-service (QoS) treatment for iSCSI traffic.
Topics:
iSCSI Optimization Overview
Default iSCSI Optimization Values
iSCSI Optimization Prerequisites
Configuring iSCSI Optimization
Displaying iSCSI Optimization Information
iSCSI Optimization Overview
iSCSI is a TCP/IP-based protocol for establishing and managing connections between IP-based storage devices and initiators in
a storage area network (SAN).
iSCSI optimization provides a means of monitoring iSCSI sessions and applying quality of service (QoS) policies on iSCSI traffic.
When enabled, iSCSI optimization allows a switch to monitor (snoop) the establishment and termination of iSCSI connections.
The switch uses the snooped information to detect iSCSI sessions and connections established through the switch.
iSCSI optimization allows you to reduce deployment time and management complexity in data centers. In a data center network,
Dell EqualLogic and Dell Compellent iSCSI storage arrays are connected to a converged Ethernet network using the data center
bridging exchange protocol (DCBx) through stacked and/or nonstacked Ethernet switches.
iSCSI optimization functions as follows:
Auto-detection of EqualLogic storage arrays the switch detects any active EqualLogic array directly attached to its ports.
Manual configuration to detect Dell Compellent storage arrays where auto-detection is not supported.
Automatic configuration of switch ports after detection of storage arrays.
iSCSI monitoring sessions the switch monitors and tracks active iSCSI sessions in connections on the switch, including
port information and iSCSI session information.
iSCSI QoS A user-configured iSCSI class of service (CoS) profile is applied to all iSCSI traffic. Classifier rules are used
to direct the iSCSI data traffic to queues that can be given preferential QoS treatment over other data passing through the
switch. Preferential treatment helps to avoid session interruptions during times of congestion that would otherwise cause
dropped iSCSI packets.
iSCSI DCBx TLVs are supported.
The following illustration shows iSCSI optimization between servers and a storage array in which a stack of three switches
connect installed servers (iSCSI initiators) to a storage array (iSCSI targets) in a SAN network. iSCSI optimization running on
the master switch is configured to use dot1p priority-queue assignments to ensure that iSCSI traffic in these sessions receives
priority treatment when forwarded on stacked switch hardware.
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